1. Field of the Invention
The present invention relates to a method for fabricating a liquid crystal panel, and more particularly, to a method for fabricating a liquid crystal panel in which a liquid crystal cell process is performed after a glass substrate is attached on a thin plastic substrate using a thermal sensitive adhesive and then the adhesive and the glass substrate are removed from.
2. Discussion of the Related Art
Liquid crystal displays (LCDs) are being increasingly used as a next generation display device for its a low power consumption, easy portability, its advanced technology and its high added-value.
Among the various types of LCDs, an active matrix LCD having switching elements that can control voltage On/Off of the respective pixels is notable for its high resolution and outstanding display of moving pictures.
In general, an LCD is fabricated by a method including forming an array substrate and a color filter substrate through an array substrate forming process in which a pixel electrode is formed, and a color filter substrate forming process in which a color filter and a common electrode are formed, and performing a liquid crystal cell process in which a liquid crystal material is filled between the array substrate and the color filter substrate.
The driving principle of the LCD is based on the optical anisotropy and polarization of liquid crystal. Because liquid crystal molecules have a thin and long structure, they have a directionality in their molecular arrangement. Their arrangement direction is controllable by artificially applying an electric field to the liquid crystal.
If the arrangement direction of the liquid crystal molecules is artificially controlled, the arrangement of the liquid crystal molecules is changed. Accordingly, when incident light is refracted in the arrangement direction of the liquid crystal molecules by the optical anisotropy, the LCD device is capable of displaying an image.
FIG. 1 is a schematic view illustrating a related art LCD.
Referring to FIG. 1, the LCD 10 includes a lower substrate 14 on which a thin film transistors (TFTs) array is formed, an upper substrate on which color filters are arranged, and a liquid crystal layer 13 interposed between the upper substrate 12 and the lower substrate 14.
The upper substrate 12, the lower substrate 14 and the liquid crystal layer 13 form a liquid crystal panel.
While the upper substrate 12 and the lower substrate 14 have the TFT arrays and the color filters, respectively, they are omitted in FIG. 1.
The LCD further includes a backlight that supplies light for displaying an image.
The TFTs array formed on the lower substrate 14 transmits or controls electrical signals, the liquid crystal layer 13 changes its molecular arrangement depending on an applied voltage, thereby controlling light transmittance. Light controlled through the above processes enables the desired images to be displayed while passing through the upper substrate 12 having the color filters formed thereon.
The LCD is also provided on its both outer surfaces with a lower polarizer 15 and an upper polarizer 11.
Thus, the fabrication of the LCD is completed by a process of forming an upper panel and a lower panel together with a process for forming liquid crystal cells of pixel unit, a process of forming an alignment layer and rubbing the formed alignment layer, a process of attaching the upper panel and the lower panel, and a process of filling liquid crystal between the upper panel and the lower panel attached.
Meanwhile, the glass substrate used as a base substrate of the upper panel and the lower panel is replaced by a plastic substrate because the plastic substrate is thinner and lighter than the glass substrate and thus reduces the risk of fracture.
However, when the aforementioned processes are performed on the thin plastic substrate, a local micro-deformation is caused during an adsorbing process of production due to the thinness and low hardness of the plastic substrate. This results in a micro-failure.
In addition, because the plastic substrate is thin, considerable warping is generated due to its heat-resistance, which results in the lowering of manufacturing productivity while a robot a carrier system transfers the plastic substrates.
Accordingly, when the plastic substrate in the liquid crystal panel is 0.03 mm thick, it is necessary to change the structure of the manufacturing facility and establish a new production line so as to secure the safety with respect to the adsorption, resulting in an enormous additional investment. Also, because the plastic substrate has many local failures, it is problematic because the process yield is low.